Perceiving the Imperceptible in Atrial Macro-Reentry: Ultrahigh Resolution Mapping to Characterize the Critical Isthmus.

Abstract

Mapping macro-reentrant atrial tachycardias occurring late after prior atrial fibrillation ablation or atrial surgery requires identification of the critical isthmus necessary for maintaining the circuit.1 The current most widely accepted approach is a combination of entrainment and 3-dimensional (3D) electroanatomic mapping with insights into atrial anatomy. 3D electroanatomic mapping systems have been shown to be important in delineating complex circuits, particularly in the setting of abnormal atrial anatomy, multiple circuits, and regions of scar.2–6 However, entrainment mapping has remained central to determining which parts of the atria are directly involved in the flutter circuit versus those that are activated passively.7,8 See Article by Latcu et al The recent advent of an ultrahigh resolution 3D electroanatomic mapping system (Rhythmia, Boston Scientific) provides a level of detail not previously possible9 and may lead to a rethinking of the standard approaches to arrhythmia management. The Rhythmia mapping system allows real-time automated electrogram annotation and the rapid acquisition of thousands of activation points using the IntellaMap Orion (Boston Scientific) mapping catheter, which has 64 flat microelectrodes (0.8 mm diameter) with a 2.5 mm interelectrode distance (center-to-center) arranged in a basket configuration of 8 splines. Multiple feasibility studies from different centers have shown this mapping system to be safe and accurate in the 3D electroanatomic mapping of both atrial and ventricular arrhythmias.10,11 In the current issue of the Journal, Latcu et al12 evaluated the utility of the Rhythmia mapping system in 33 patients with scar-related atrial tachycardias either after atrial fibrillation ablation or after surgical mitral valve repair. They observed 26 macro-reentrant atrial tachycardias, 4 micro-reentrant atrial tachycardias, and 1 focal atrial tachycardia …